When someone does pull the trigger to build a reproduction 3' gage locomotive, something that I believe is just a matter of time, a prototype such as this would make tremendous sense.
The straight boiler (no wagon top) is the least expensive type of locomotive boiler to build. The outside frames can easily be fabricated from flame cut steel plate. The cast driving wheel centers are simplified, with no crank hubs to cast in. The outside crank hubs are a no-brainer, made from flame cut steel plate. The slide valve cylinder blocks, while complicated, are about the simplest type of cylinders to make patterns for and cast, with four sets that I know of having been cast in fairly resent memory. The basic U-shaped tender tank is something any decent fab shop can build.
All of the above can be easily accomplished with today’s manufacturing techniques and infrastructure. All that needs to be added is determination, and you guessed it, money.
This photo is from:
[southern-railway.railfan.net]